Ambient-protecting organic light transducer grown on pentacene-channel of photo-gating complementary inverter

Abstract

Usually, organic thin-film transistors (TFTs) including pentacene TFTs have a bottom gate device architecture with an open back channel surface, thus requiring an ambient protecting layer on the organic devices. If the requested protecting layer has another function by chance, even more unique applications may be developed on the organic device. For such bi-functional applications, we have investigated a hydrophobic 6,13-pentacenequinone (PQ) crystalline layer on pentacene TFT for two reasons. Firstly, crystalline pentacenequinone–crystalline pentacene is quite similar to SiO₂–Si structure. Because the PQ is a molecular form of already-oxidized pentacene, diffusion of water and oxygen molecules into channel pentacene may not be easy when the PQ layer is well grown on pentacene making a good PQ–pentacene interface. Moreover, the PQ protects the pentacene from high intensity ultraviolet (UV) light, since it transduces the UV into green light. After we had fabricated pentacene-based complementary photo-gating inverter devices, our inverters with the crystalline-grown PQ on pentacene channel demonstrated strong ambient-endurance preserving good inverter characteristics for 60 days under quite humid ambient air, and they also demonstrated dynamic photo-gating at a low voltage of 5 V without any UV-induced degradation.